textproduct: Albany

WHAT HAS CHANGED

Adjusted temperatures down by 4-6 degrees across northern areas now through the rest of tonight as calm winds and thin high clouds have allowed temperatures to drop into the upper 30s to mid 40s. Added some (very) patchy frost back into the forecast across far northeastern Hamilton County. Also adjusted daytime highs down from the NBM each of the next several days, especially on Sunday with widespread clouds and showers. Finally, bumped up PoPs and qpf Sunday night into Monday.

KEY MESSAGES

1) Widespread rain expected this afternoon through Sunday afternoon. A beneficial 0.5 to 1.5" of rain is expected, which will not be enough to result in any flooding concerns.

2) Trending warmer Tuesday and Wednesday. After a dry Tuesday, shower chances increase again for the middle to end of the week.

DISCUSSION

KEY MESSAGE 1... As of 2:15 AM EDT...Current sfc analysis shows a 1033 mb sfc high centered over E/SE Quebec, centered beneath strongly confluent upper-level flow. This is leading to subsidence and dry conditions across our region for the time being. Given the proximity to the sfc high and the fact that high clouds remained very thin for northern areas the first half of the night, temperatures dropped a few to several degrees below the previous forecast, with upper 30s to mid 40s in these areas per latest NYS Mesonet obs. Given this, some localized, patchy frost can't totally be ruled out through the next few hours across interior Hamilton and northern Warren Counties. Current satellite imagery does show the high clouds beginning to thicken for these areas, so temperatures shouldn't drop more than a few degrees from current readings.

These high clouds are associated with a negatively tilted upper shortwave seen on GOES 16 WV imagery tracking into the south-central Great Lakes, and an associated sfc low that will track into the Ohio Valley this morning. Current radar imagery shows areas of rain across PA right now, but given strong confluence aloft and subsidence leading to very dry low to mid-level air as seen on the 00z KALY sounding, it will take several more hours for precip to make it into our region. Guidance has finally converged on start timing of rain today. Showers should begin in the southern Catskills/Mid Hudson Valley late this morning/early afternoon, begin around the Capital District late this afternoon into this evening, and then overspread areas north and east early tonight. Today will therefore be a relatively nice day from the Capital District north and east with highs in the 60s, although areas south and west will be cooler with the aforementioned showers, especially this afternoon.

Tonight, primary sfc low tracks to our west through the Great Lakes while a strengthening SE LLJ will lead to an influx of Atlantic moisture that will overlap with a sloping band of mid-level FGEN and result in widespread rain across the region. As we head through the night into tomorrow, coastal inverted trough/secondary low will develop, and a warm front will approach from the south. PWATs increase to 1.1-1.3" with forcing mechanism transitioning to mainly isentropic lift/warm advection. Rain continue through much of the day Sunday, tapering to showers Sunday evening. With low-level cold air dammed at the sfc, Sunday looks quite cool, as highs will only be in the upper 40s (terrain) to mid 50s (valleys). We collaborated with neighboring offices to lower temps Sunday from the NBM as it still seems too warm, even though it is finally beginning to catch onto the cooler solution we have been advertising for the last couple days.

By the time rain tapers off Sunday evening, rainfall amounts will range from around or just under a half inch for northeastern areas to up to 1.5" for the southeastern Catskills and Mid Hudson Valley. With many areas having not seen appreciable rainfall in the last week or so, this will be a very beneficial rain. These rainfall amounts and rainfall rates do not look to be high enough to result in any flooding issues. Lack of instability should prevent any thunder today through most of tomorrow, although a tongue of elevated instability (showalter values <0) reaching into southern zones late Sunday may allow for a few non-severe rumbles of thunder in the evening or early Sunday night with any lingering showers.

While there is good agreement for at least a brief break in the rain Sunday evening/early Sunday night, confidence decreases for late Sunday night into Memorial Day. Some sources of guidance continue to show phasing between northern and southern stream disturbances over the Ohio Valley, with another surge of Gulf moisture into the region ahead of the strengthening upper forcing. NAM/GFS have been the wettest, while CMC/Euro have slightly less interaction between these features and drier conditions Monday morning. We are still seeing some rather large run-run jumps with the relevant upper-level features in the various sources of model guidance. Therefore, have taken a blended approach for now, but will mention that current line of thinking leans slightly in favor of GFS/NAM, even in their qpf seems overdone. Fortunately, showers chances should decrease through Monday afternoon with some breaks of sun possible later in the day. Highs will likely range from 60s (terrain) to 70s (valleys).

KEY MESSAGE 2...As we head into the middle of next week, initially zonal flow aloft becomes more northwesterly as upper ridging amplifies over the center of the country, forming an omega block towards the end of next week. We will see a warming trend Tuesday into Wednesday. However, NBM once again seems to be significantly over-estimating high temperatures, so we trended the forecast lower in collaboration with neighboring offices (TUE) and WPC (Wed). Wednesday highs may be trended even lower from the current forecast over the coming days. Highs in the upper 70s to low 80s seems reasonable given the pattern and MEX/ECM guidance.

While we dry out Tuesday, there is decent agreement in the medium range guidance for an upper shortwave and associated cold front within the NW flow to track through the region at some point towards the middle of next week, although timing is uncertain. At this point, Wednesday seems like the most likely timeframe, but this will be subject to change. Will likely see a few showers, and possibly some thunder if the frontal passage coincides with daytime heating. Temperatures then trend cooler, back to near normal levels for the second half of next week. Additional shortwaves embedded within the amplified NW flow may bring some additional chances for showers at times as well Thursday or Friday.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Flying conditions are currently VFR across the region with light to calm winds. IR satellite shows widespread mid and high level clouds over the region, with few-sct cigs around 12 kft and a bkn-ovc high deck around 20-25 kft. Radar imagery and surface observations currently show light rain over northern PA and NJ. Although the day will start off dry, this rainfall will be slowly lifting northward towards the area for today.

Ceilings will be lowering during the morning hours and some light rain will begin as early as 16z at KPOU and 21z at KALB/KPSF. When precip begins, both visibility and ceilings will initially be VFR, but after a few hours, visibility and possibly ceilings will lower to MVFR levels. Further north, KGFL may stay dry till about 00z, but some patchy areas of light rain are possible after that, so will include a PROB30 for MVFR rainfall there. The initial batch of rain may let up towards the middle of the night and but another round of steadier and slightly heavier rainfall is expected for all sites by the late night hours and towards daybreak Sunday. This rainfall will lower visibility and ceilings down to solid MVFR for all sites, and some IFR cannot be ruled out, although that would be more likely for after 12z Sunday.

East-southeast winds will be 5-10 kts during the day today. South to southeast winds at similar speeds will continue into tonight as well.

Outlook...

Sunday Night: Moderate Operational Impact. Chance of SHRA. Memorial Day: Moderate Operational Impact. Chance of SHRA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Low Operational Impact. Slight Chance of SHRA...TSRA. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Low Operational Impact. Slight Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.